Phase One H 5 - Manual (Page 23)

Unsharp Mask
The name “unsharp mask” (USM) can be misleading. Using this tool
actually gives an apparent increase in image sharpness by enhancing
the edge differences between pixels of different colors.
When applied to an image, the software evaluates the contrast
differences between pixels and either enhances the difference or not,
based on your settings.
There are two controls over the USM:
Amount
The amount of change is entered here as a percentage.
The higher the setting, the more sharpening will be applied.
Threshold
The threshold level controls at what level the sharpening will begin.
At the default “0” setting the sharpening amount is applied to every
pixel.
A third option found in many imaging programs, Radius, is fixed in the
software application at about 1 pixel.
Using this tool to attempt to sharpen
an image that is clearly out of focus
will not give a pleasing result.
However, an image that appears to
be soft, with low color contrast, can
be significantly enhanced by careful
application of USM.
The Gradation Curve pane also reads Input and Output values. These
numbers show the “before” and “after” values of the pixels at the point
you placed on the curve. The Input value shows the brightness of the
pixel before the curve is applied, and the Output value shows the
brightness of the pixel after the curve is applied.
The key to both Tonal Range and Gradation Curves is to be conservative
with their use. Using these tools to attempt to correct an image that was
poorly exposed will not result in a high quality image.
The Film Curve tab shows the default film curve and ISO value of the
Phase One H 5.
5.6
Tools
5.7
Tools